The invention relates to systems for supplying battery-powered electric vehicles with fully charged batteries.
The disadvantages of vehicles powered by an on-board supply of fossil fuel are well recognized. Electric vehicles have long been proffered as a desirable alternative potentially having a less harmful impact on the environment and reducing noise pollution without compromising power. Successful electric vehicle systems have been implemented for mass transportation where the electric power is provided to the vehicles by overhead wires for trolleys and electric buses on fixed routes or by third rails for electric trains on fixed track. Systems have also been proposed in which the electrical energy is delivered to the moving vehicle without attached wires through electromagnetic induction. These systems generally require a fixed underground induction track.
The electrically powered automobile and truck, however, present a different problem because they must carry their electrical energy with them in storage batteries. Battery-powered electric vehicles have the major drawback that they have a limited range before the batteries wear down and need recharging. This problem is faced by fossil-fuel powered vehicles, too, which must also carry their fuel with them. Unlike the electric vehicles, however, gasoline and diesel vehicles have a well established distribution system for re-fueling the vehicle in practically any locality on demand. Service stations providing gasoline and diesel fuel are well distributed along highways and throughout urban and rural regions alike.
As one way of increasing the range of electric vehicles, designers have sought to improve the design of the vehicles themselves. They have tried to make the vehicles lighter and have aimed at more aerodynamically efficient shapes to reduce air resistance. The battery assemblies, which may weigh as much as 800 pounds (365 kilograms) or so, have tended to be located in the center of the vehicle in the vicinity of the vehicle center of gravity for better performance. Improved designs have also been made to the batteries themselves so that they are lighter, or have a greater capacity for their size or weight, or can be recharged faster or more efficiently.
Examples of electric vehicle designs incorporating large battery assemblies are shown in U.S. Pat. Nos. 3,983,952 and 4,216,839 and British Patent No. 2,108,443. U.S. Pat. No. 3,983,952 to McKee discloses an electric vehicle using a long roll-out tray of batteries easily rolled into or from a housing which also comprises a structural backbone of the vehicle. The roll-out tray of batteries is accessible from the front of the vehicle. U. S. Pat. No. 4,216,839 to Gould discloses an electric vehicle with minimum weight by utilizing a combined body and chassis formed entirely of plastic material, molded and bonded into an integral composite structure which includes a central longitudinal hollow beam which holds the batteries for powering the vehicle. The batteries rest on slidable trays in the hollow beam. To replace the batteries, the trays are slid out of the hollow beam from the front of the vehicle and new batteries are slid back into the beam on the trays. British Patent No. 2,108,443 to Appleyard discloses an electric vehicle with a chassis containing one or more traction battery cassettes adapted for easy removal for recharging and replacement by cassettes or recharged batteries. The battery cassette handler inside the vehicle comprises lifting cables, an actuator for the cables, brackets, and pins or other engagement means for supporting the cassette from the brackets when lifted into position.
Other patents show devices for installing and removing the battery assemblies from the vehicle for charging or exchange. U.S. Pat. No. 3,799,063 to Reed discloses an electric vehicle battery changing and positioning device that includes lift arms pivotally (and permanently) mounted to the vehicle frame. The arms are attached at their free ends to a battery tray and cover. The arms may be hydraulically rotated to move the battery tray and cover through an arc from an inner position on the vehicle to an outer position spaced from the vehicle to facilitate changing or servicing. U.S. Pat. No. 3,834,563 to Teti discloses a battery carrier for moving the batteries of mine tractors and the like into and out of a receiving compartment. Like the Reed patent, the Teti device includes pivoted arms, the free ends of which support the battery or batteries. The arms pivot to move the batteries into and out of their compartment.
Yet other patents are directed to facilities for exchanging battery assemblies. U.S. Pat. No. 4,334,819 to Hammerslag discloses a battery charging system for battery powered vehicles at a battery transfer station. The battery is removed from the vehicle and transferred to either a conveyor charging system or to storage and charging bays. The battery is removed from above, out of the vehicle's trunk through a crane that lifts the battery out of the vehicle and onto the conveyor system. U.S. Pat. No. 5,091,687 to Meyer discloses a charging system with a circular magazine which is pivotable about a central axis. A gripper device pulls the battery out of the side of the vehicle and into the circular magazine whereby another battery is pushed into the vehicle from the circular magazine. U.S. Pat. No. 4,450,400 to Gwyn discloses a battery replacement system for electric vehicles with a carriage-elevator structure which is arranged in front of a battery station to transfer selected batteries between the charging station and a parked stationary vehicle. The vehicle and the charging station are provided with roller support units adapted to bear the battery weight and permit manual pushing and/or pulling of individual batteries to or from the elevator. The batteries are rolled out of the rear of the vehicle and onto the elevator and a new charged battery is put in its place. U.S. Pat. No. 4,102,273 to Merkle et al. addresses the problem of positioning an electric vehicle at a station for replacing the batteries. The Merkle patent provides a carriage device for moving the whole vehicle forward and back over a lift or dolly for replacement of the batteries.
The above examples represent a haphazard approach to the problem of dealing with 800-pound (365-kilogram), bulky battery assemblies for electric vehicles. The known approaches involve a compromise in ease of use or convenience, are not such as to enable them to be adopted for widespread use, and do not necessarily provide adequate collision protection for the vehicle occupants or the batteries themselves.